The present invention relates to a method of inhibiting corrosion, particularly in oil field producing equipment. In one aspect, the method of the present invention employs a compound containing sulfur and nitrogen.
Wells producing from subterranean formations frequently produce high concentrations of salt water which present a severe corrosion problem, particularly at temperatures above 250.degree. F. Corrosion is further increased with the presence of oxygen, carbon dioxide, hydrogen sulfide and/or organic and inorganic acids.
Nitrogen containing compounds are known to act as corrosion inhibitors. For example, various amines are effective to inhibit corrosion. A number of patents disclose corrosion inhibitors containing sulfur and/or nitrogen, e.g., sulfur - U.S. Pat. Nos. 3,809,655, 3,759,956, 3,755,176, 3,158,476, 2,880,180, 3,404,094, 3,197,403, 3,969,414; nitrogen - 3,445,441, 3,450,646, 3,976,593; sulfur and nitrogen - 3,414,521, 4,450,138.
U.S. Pat. No. 4,450,138, for example, discloses among other things, the reaction of thiols with epichlorohydrin followed by the reaction with amines.
U.S. Pat. No. 4,446,056 discloses S containing compositions prepared by reacting hexahydrotriazines, in the presence of a Lewis acid, with S or S containing compounds.
U.S. Pat. No. 4,673,436 discloses the use of a thio substituted quaternary ammonium salt.
There are several patents which disclose the use of N-S containing compounds for use as corrosion inhibitors in pickling operations. Pickling is a process for the removal of scale, oxides, and other impurities from metal surfaces by immersion into an inorganic acid. U.S. Pat. Nos. 2,425,320, 2,586,331, 2,606,155 are representatives of pickling inhibition patents. However, there is no teaching in these references that the N-S compounds are effective in inhibiting corrosion of oil field producing equipment.
Other U.S. Patents which disclose corrosion inhibitors include U.S. Pat. Nos. 3,634,270, 3,969,255, and 4,536,302. These references, however, do not disclose the corrosion inhibitors of the present invention.